Yukino is Shichiroji's lover and the woman who saved his life when Shichiroji's escape pod washed ashore on the river underneath the Firefly House. Indebted to Yukino, Shichiroji helps her run the Firefly House and claims that he had abandoned the samurai life.

However, it is one of Yukino's fears that the old samurai hasn't quite forgotten fighting. When Shichiroji joins Kambei and the others on their journey to K

anna village, Yukino waits for him, expecting him to return with "a mountain of treasure" as in the old tale of "Peach Boy" with which they tease Shichiroji with.

As the series progresses, Yukino seems to be very sisterly towards Kirara and is aware of her hidden love for Kambei.